As medical and technical knowledge advances, there are a growing number of situations where there may be significant therapeutic value in having the ability to inject a drug or tissue-engineered material directly into a precise location on the epicardium of a patient. An example of one such situation is the infusion of therapeutic agents, such as radioactive compounds, for the treatment of tumors. With respect to tissue-engineered materials, stem cells and biopolymers have been injected into the heart in order to treat, for example, myocardial infarct lesions. Until relatively recently, however, the delivery of these substances had necessitated the cracking open of the rib cage of a patient to access the heart directly due to the fact that the heart is extremely well-protected and difficult to access. For a variety of reasons, including the possibility for infection and long recovery times, a minimally invasive procedure where the heart is accessed from below the xiphoid process is preferred.
While the access problem has been solved for certain procedures, the performance of surgical procedures on the heart remains a technical challenge not only because the surgeon cannot directly see the heart during the operation, but also because the heart continues to move during the procedure. The movement caused by pumping makes it extraordinarily difficult to achieve any accuracy in the location of the injection when using prior art minimally invasive prior art devices.
One prior art device, the PerDUCER pericardial access device, is presently used for minimally invasive access to the pericardial space, whether to insert a guide wire, inject a drug or withdraw some pericardial fluid when indicated. As disclosed in the art, the device comprises a 21-gauge needle housed inside a 12-French stainless steel sheath tube that is about 20 cm in length. The distal end of the sheath tube is bonded to a plastic tube with a tapered end and a half-moon cross-sectional shape. The tapered end of the plastic tube further has a hemispherical side hole that is pressed against the pericardium during the procedure. A vacuum suction is then applied to the side hole, which forces a portion of the pericardium to be pulled into the side hole and creates a bleb. A guide wire or other sharp device is then introduced into the bleb to permit direct injection directly into the pericardial space or to allow for future access. A drawback to this device, however, is that it does not permit injection or entry into the pericardium at an exact, predetermined location and depth due to the distortion of the pericardium caused by the formation of the bleb. Moreover, this device does not permit injection into the epicardium.
In view of the foregoing, a need has been recognized in connection with improving upon the shortcomings and disadvantages of current systems and methods for delivering injections or other therapeutic agents to a precise location within the pericardial sac or into the epicardium itself.
For a better understanding of the present invention, together with other and further features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, and the scope of the invention that will be pointed out in the appended claims.